Cathode ray tube



April 13,1937. VON ARDENNE AL 2,077,288

' CATHODE RAY TUBE Filed May 20, 1932 JnVen/ors:

Patented Apr. 13, 1937 UNITED STATES PATENT OFFICE lin,

Germany; said von Ardenne a'ssignor to Radioaktiengesellschaft D. S.Loewe, Berlin- Steglitz, Germany, a company of Germany Application May20, 1932, Serial No. 612,410 In Germany May 23, 1931 12 Claims. (01.250-215)" The present invention relates to Braun tubes and similarcathode ray recorders, cathode ray oscillographs, Braun tubes fortelevision purposes and the like, in which deflection of the cathode rayout of its original direction is performed by special auxiliaryelements, and more particularly deflecting plates. Apparatus of thisnature are accompanied by the fact that with increasing rate ofdeflection there occurs a widening of the cathode ray following itsdeflection, and accordingly a widening of the fluorescent spot.

This dispersion of the cathode ray, which accordingly depends on therate of deflection thereof, would appear to be due to the followingreason: The cathode ray is formed by a plurality of electrons, whichadvance in the direction of the ray at a very high speed-approximatelyHBO- the speed of light. The space charge cloud formed by this ionic raynow attempts to disintegrate insofar as special means are not providedfor wholly or practically maintaining the concentration of the ray. Nowthe cathode ray certainly creates by ionization by way of collision inthe existing gas a certain number of positive ions which, however, arenot sufficient either in their number or in their efiectivecross-section to I compensate the spreading forces of the space chargecloud. This is due on the one hand to the fact that the ions possessmerely a short life, and generally speaking, due to the relatively slowkinetic rate of movement, are unable to follow up the moved cathode ray,and accordingly are left back by the ray, in which the same shortlybefore constituted an embedded positive charge which preventeddispersion of the space charge.

According to the invention, a gas, therefore, is employed, whichpossesses a very high kinetic speed, preferably hydrogen gas, a gas,therefore, the ions of which diffuse with the greatest rapidity, andaccordingly result in a very large effective cross-section. Anadditional requirement foraccomplishing an appreciable effectivecross-section is, as stated above, a duration as lengthy as possible ofthe positive ions in the gas employed. When employing a gas according tothe invention the positive ion charges contained in the ionic ray will,assuming the rate of deflection is not over-excessive, follow thecathode ray upon the deflection thereof and, in-

60 sofar as due tothe Maxwell rate of distribution they are unable to dothis, will be replaced by new ions present at the particularpointtouched by the cathode ray or generated by reason of ionization bycollision.

55 When employing hydrogen gas for the space traversed by the deflectedcathode ray there will preferably be used a tungsten thorium cathode.Barium alloy cathodes, however, are also suitable for discharge vesselsof this nature. f

According to the additional subject. matter of the invention,-the spacetraversed by the cathode ray is ionized by special ionization sources.Suitable for this purpose are certain known hot electrodes, light arcs,mercury arcs, radio-active substances and the like. In the mostconvenient fashion, however, the ionization will be performed by glowdischarge between special auxiliary electrodes. When employing anionized space, it is no longer of considerable importance what nature ofgas is made use of, as ions will exist in sufiicient number at theparticu- I lar points touched by the ray. On the other hand, however,the ionization of the space should not be carried to such extent thatthe ionic ray is neutralized prior to touching the fluorescent layer. Itis furthermore essential that the ion ization of the space takes placeas evenly as possible in order to avoid fluctuations in the focussing ofthe ray.

As already statedrabove, certain hot electrodes may be made use of forcreating the positive ions. According to the additional subject matterof the invention, the oneelectrode is to-be employed for creatingv boththe negative electrons as wellas the positive ions ionizing the space.From a practical standpoint this may be accomplished in simple fashionin such manner that the electrons emitted by the hot cathode receivetheir acceleration from the anode field of the Braun tube, whilst theemitted ions are moved for the greater part through the field of aspecial auxiliary cathode, i. e., in such manner, therefore, that thehot electrode on the one hand forms the cathode of the Braun tube and onthe other hand the anode of the ion-generating device. v

In the figures of the appended drawing some possible embodiments of thisinvention are illustrated. a

In Fig. 1, means of 2 difierent kinds for producing the auxiliaryionization are illustrated, viz., one auxiliary discharge gap and aradioactive substance, whereas Fig. 2 illustrates the provision of twoauxiliary discharge gaps.

The embodiment of our invention wherein only one additional auxiliaryelectrode is provided coacting with the cathode of the cathode ray tube,has not been shown.

In both figures, I is the cathode ray tube which may be filled with gasof an adapted pressure and which may contain any desirable electrodesystem, comprising for instance a cathode l0, an anode I i anddeflecting elements which may consist of pairs 12 and [3 of deflectingplates. 2 is the fluorescent screen, 3 and 6 are the tubular chambersopened to the gas room of the cathode ray tube and wherein, in thearrangement according to Fig. 1, either the auxiliary electrodes 4 and 5or the radio-active substance 1 may be arranged to produce the auxiliaryionization.

In Fig. 2, 6 and 5 on the one hand, 8 and Son the other hand, are thetwo pairs of auxiliary electrodes.

We claim:

1. A cathode-ray tube comprising hydrogenfilling a hot cathode, an anodearranged in operative relationship thereto for producing a cathode ray,said cathode ray ionizing the gas-filling and acting in this Way asmeans for initiating ionization, a plurality of deflecting plates, andadditional means for initiating ionization, comprising twopairs ofauxiliary electrodes arranged symmetrically toone another.

2. A cathode-ray tube comprising hydrogenfilling a hot cathode, an anodearranged in operative relationship thereto for producing a cathode ray,said cathode ray ionizing the gas-filling and acting in this way asmeans for initiating ionization, a plurality of deflecting plates, andadditional means for initiating ionization, comprising two pairs ofauxiliary electrodes arranged symmetrically to one another inside ofseparate tubular chambers.

3. In an electric discharge device the combination comprising means toproduce a cathode ray, apermanent gas atmosphere adapted to becomeionized when traversed by the cathode ray, and an auxiliary ionic sourcefor maintaining the focussing of the cathode ray even in the case ofhigh and fluctuating rates of deflection.

4. In an electric discharge device the combination comprising means toproduce a cathode ray, a permanent hydrogen atmosphere adapted to becomeionized when traversed by the cathode ray, and an auxiliary ionic sourcefor maintaining the focussing of the cathode ray even in the case ofhigh and fluctuating rates of deflection.

5. In an electric discharge device the combination comprising means toproduce a cathode ray, means to deflect the cathode ray, a pennanent gasatmosphere adapted to become ionized when traversed by the cathode ray,and an auxiliaryionic source for maintaining the focussing of thecathode ray even in the case of high and fluctuating rates ofdeflection.

6. The combination comprising an electric discharge device, means toproduce a cathode ray in said discharge device, means to deflect thecathode ray, a permanent gas-atmosphere in said discharge device adaptedto become ionized when traversed by the cathode ray, and an auxiliaryionic source for maintaining the focussing of the cathode ray even inthe case of high and fluctuating rates of deflection.

'7. In an electric discharge device the combination comprising means toproduce a cathode ray, a permanent gas atmosphere adapted to becomeionized when traversed by the cathode ray, and an auxiliary ionic.source for maintaining the focussing of the cathode ray even in the caseof high and fluctuating rates of deflection, said auxiliary ionic sourcecomprising auxiliary electrodes.

8. In an electric discharge device the combination comprising means toproduce a cathode ray, a permanent hydrogen atmosphere adapted to becomeionized when traversed by the cathode ray, and an auxiliary ionic sourcefor maintaining the focussingo'f the cathode ray even in the case ofhigh and fluctuating rates of deflection, said auxiliary sourcecomprising auxiliary electrodes.

9. In an electric discharge device the combination comprising means toproducea cathode ray, means to deflect the cathode ray, a permanent gasatmosphere adapted to become ionized when traversed by the cathode ray,and an auxiliary ionic source for. maintaining the focussing of thecathode ray even in the case of high and fluctuating rates ofdeflection, said auxiliary ionic source comprising auxiliary electrodes.

10. In an electric discharge devicethe com-:

bination comprising means to produce a cathode ray, a permanent gasatmosphere adapted to .become ionized when traversed by thecathode ray,and an auxiliary ionic source for maintaining the iocussing of thecathode ray even in the case of high and fluctuating rates. ofdeflection, said auxiliary ionic source comprising auxiliary electrodes,one of said electrodes being employed as electronic source for thecathode ray.

11. In an electric discharge device the combination comprising means toproduce a cathode ray, a permanent hydrogen atmosphere adapted to becomeionized when traversed by the cathode ray, and an auxiliary ionic sourceformaintaining the focussing of the cathode ray even inthe case of highand fluctuating rates of deflection, said auxiliary ionic sourcecomprising auxiliary electrodes, one of said electrodes being employedas electronic source for the cathode ray.

12. In an electric discharge device the combination comprising means toproduce a cathode ray, means to deflect the cathode ray, a permanent gasatmosphere adapted to become ionized when traversed by the cathode ray,andan auxiliary ionic source for maintaining theiocussingof the cathoderay, even in the case of high and fluctuating rates of deflection, saidauxiliaryionic source comprising auxiliary electrodes, one of saidelectrodes being employed as electronic source for the cathode ray. yMANFRED voN ARDENNE;

SIEGMUND LOEWE. h

